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will power base converter fit on a CDX?
CommanderBubba - Dec 20, 2003
    CommanderBubba Dec 20, 2003 
I currently own a CDX and use that.

Now I've recently come into some old games and I'm looking for a power base converter. I know they don't fit on top of the Mk II genesis/megadrive models, but I was wondering if anyone has ever tried plugging one into a CDX before.

Part of the reason I'm wondering is because I'm looking on eBay and seeing several collection sets that include both a Gen MkI and the converter for almost the same price as the lone Converter; furthermore buying a MkI genesis in really good cheap is only about $10 in some cases, or less.

So, I'm just wondering before I buy a bunch of stuff I don't actually need if a converter itself fits onto the CDX.

(I once owned a CDX and MkI Genesis; see my other thread in the SMS forum).

    Pearl Jammzz Dec 20, 2003 
it would fit in the hole I believe....I doubt it would sit flush but it might sit good enuf. If you send me a CDX i'll try it out on my PBC Ã

    Arakon Dec 20, 2003 
there's a model 2 SMS adapter too, which is cart sized and fits into any genny.. not entirely sure if the cdx even has the SMS mode, but I think it did.

    Pearl Jammzz Dec 20, 2003 
i believe that only the model 3 didn't have the chip for SMS. I could be wrong though, but I am fairly positive.

    ExCyber Dec 20, 2003 
Nomad doesn't, and from what I've heard it's the sole Sega-produced model that doesn't (AFAIK Sega is not involved in the production or distribution of the so-called "Model 3" aside from licensing the use of the name - it has other quirks too, such as the TAS bug in Gargoyles that most emulators exhibit). I'm not sure about the JVC Wondermega/X-Eye, though I seem to recall reading someone who said it does work.

    Mask of Destiny Dec 20, 2003 

  
Originally posted by ExCyber@Dec 20, 2003 @ 11:11 PM

Nomad doesn't, and from what I've heard it's the sole Sega-produced model that doesn't (AFAIK Sega is not involved in the production or distribution of the so-called "Model 3" aside from licensing the use of the name - it has other quirks too, such as the TAS bug in Gargoyles that most emulators exhibit). I'm not sure about the JVC Wondermega/X-Eye, though I seem to recall reading someone who said it does work.


Doesn't the Megajet not support SMS mode? I'm pretty sure that was produced by Sega as well.

    CommanderBubba Jan 5, 2004 

  
Originally posted by Arakon@Dec 20, 2003 @ 10:27 AM

there's a model 2 SMS adapter too, which is cart sized and fits into any genny.. not entirely sure if the cdx even has the SMS mode, but I think it did.


I've never seen or heard of a model 2 SMS adapter. Was that a European release only gizmo?

I don't suppose you've got a picture of one?

Just curious.

As it turns out when I bought some other parts and games I got a converter and mk1 console anyways, so this is sort of a moot point, but I'm still curious.

   Link Hylia Jan 5, 2004 
yes, the Master System Converter works fine on a CDX, provided you stabilize it with books or packing material. the CDX also works with the 32X, with the same preperations. the CDX has most everything a Genesis Model 1 and 2 have.

This missing chip in the Genny 3, actually is a myth. without the Z80 (the chip said to have been removed for costs), most games would have tons of sound problems.

What really is missing, is the SMS mode for the VDP, and a few DMA modes, so neither PBC, 32x, or Virtua Racing work.

    ExCyber Jan 5, 2004 

  
What really is missing, is the SMS mode for the VDP, and a few DMA modes, so neither PBC, 32x, or Virtua Racing work.


I really doubt that any important DMA modes are missing. More likely the DRAM refresh signal on pin B21 is missing/wrong, so anything that depends on it for DRAM timing will not work. If anyone has a fairly nice multimeter and/or oscilliscope and a Genesis 3 this theory could be tested by looking for a KHz-range frequency on B21 (varying if the CPU is running, constant ~60KHz if it's halted according to the docs I've read).

    Mask of Destiny Jan 5, 2004 
Actually, according to Charles MacDonald (who has a Genesis 3 and an EPROM cart or two) Mode 4 (the SMS video mode) is supported on the Genesis 3 (which seems kind of silly since the complete SMS compatability mode isn't, but eh).

My thought on why the 32X does not work with the Genesis 3 was that DTAK was not available on that console. DTAK is used by the 32X to deal with conflicting cartridge access between the SH-2s and the 68K. There was a discussion about this on segadev a while back, but I don't remember the conclusion.

    snume Jan 15, 2004 

  
Originally posted by CommanderBubba+Jan 5, 2004 @ 09:41 PM--><div class='quotetop'>QUOTE(CommanderBubba @ Jan 5, 2004 @ 09:41 PM)</div><div class='quotemain'> <!--QuoteBegin-Arakon@Dec 20, 2003 @ 10:27 AM

there's a model 2 SMS adapter too, which is cart sized and fits into any genny.. not entirely sure if the cdx even has the SMS mode, but I think it did.


I've never seen or heard of a model 2 SMS adapter. Was that a European release only gizmo?

I don't suppose you've got a picture of one?

[/b][/quote]

As a matter of fact I do. bought it from some dude in the UK off eBay.

There is a ring at the bottom that comes off if you use it on the model

1 Genesis. But I've had it hooked up to my CDX, it works no problem.

I worry a little bit about the stability, tho. Luckily, I have a Genesis 2

to hook it up to. I also have a Power Base Converter but wanted this

baby for the uniqueness.

    snume Jan 15, 2004 
Oh, and dafran has one in his collection. You can see it if you go

to his site and browse the consoles section. It's in one of his many

bookcases full of games & hardware.

Dude how much money do you have sunk into that collection!!

   stack99 Jan 23, 2004 
Stupid question, but that master system converter 2 will only work in megadrive systems, or genesis' as well? thanks.

    Arakon Jan 24, 2004 
they aren't region specific.

    ExCyber Jan 24, 2004 

  
My thought on why the 32X does not work with the Genesis 3 was that DTAK was not available on that console. DTAK is used by the 32X to deal with conflicting cartridge access between the SH-2s and the 68K.


That hadn't occurred to me, and certainly sounds plausible; DTACK is the preferred mechanism for holding off completion of a 68K memory access. AFAIK that's the reason that the "lock up" areas in the Genesis memory map exist - they disable the internal DTACK generation so that it can be managed by external hardware...

    stack99 Jan 25, 2004 

  
they aren't region specific


But I thought that the cartridge size of mega drive and genny was different, and therefore you would need an adapter to play megadrive games on a genny, and therefore this device wouldn't work on a genny.??

   Mask of Destiny Jan 25, 2004 

  
Originally posted by ExCyber@Jan 25, 2004 @ 04:30 AM


  
My thought on why the 32X does not work with the Genesis 3 was that DTAK was not available on that console. DTAK is used by the 32X to deal with conflicting cartridge access between the SH-2s and the 68K.


That hadn't occurred to me, and certainly sounds plausible; DTACK is the preferred mechanism for holding off completion of a 68K memory access. AFAIK that's the reason that the "lock up" areas in the Genesis memory map exist - they disable the internal DTACK generation so that it can be managed by external hardware...


DTAK is tied to ground through a pull-down resistor on the Genesis. If it's left floating, it will default to logic 0. It's also attached to the VDP, but I'm not sure if its an input or an output. It could just be there so that the VDP will wait for a slow device when its doing DMA (which it would have to if its going to be able to do cart -> VRAM DMA when using the 32X).